Arnold E. S., Ling S. C., et al (2013). ALS-linked TDP-43
mutations produce aberrant RNA splicing and adult-onset motor neuron disease
without aggregation or loss of nuclear TDP-43. PNAS, 110(8) 736-745.
sclerosis (ALS) along with frontotemporal lobar degeneration with ubiquitinated
inclusions (FTLD-U) contribute to neurodegenerative diseases. This study investigated
the effect of mutations to the TDP-43 protein, which has been linked to motor
neuron diseases (MNDs). Using generated transgenic mice with a mutation in the
TDP-43 scientists were able to track the mutation during the developmental
process. At birth, both control and mutant of the TDP-43 were almost indistinguishable.
However, after 3 months the mutants began
to show signs of tremors which worsened with age. The TDP-43 mutant did not
need to show aggregation to show symptoms of MNDs revealed by the immunostaining.
This research provides a better understanding of loss of function mutations to
neuronal pathways and their effects on MNDs.
Generation of transgenic mice, RT-qPCR, immunoblotting, immunohistochemistry, morphometric
analysis, Quantification of motor neurons, animal behavior, electrophysiology,
nuclear-cytosolic fractionation, microarray.
Gitcho M. A., Baloh R. H., et al. (2008). TDP-43 A315T Mutation in
Familiar Motor Neuron Disease. Ann Neurol,
63 (4), 535-538
are some of the most physically devastating diseases. These motor neuron
diseases (MND) act slowly with affected individuals losing the ability to use
certain appendages, upper body, and /or lower body control and will result in
death. This study used previous works from the TAR DNA-binding protein 43 (TDP
43) as an proteopathy. DNA sequencing of TDP 43 exposed a missense
mutation, ALA-315-Thr (A-315-T) within exon 6. This alanine residue is critical
since it has been conserved in humans and distant ancestors. Of the 1,505
subjects that were sequenced, most with a MND showed a mutation with the
A-315-T residue. More evidence is needed to continue this experiment, mainly an
autopsy of affected subjects. Some MNDs are contributed to frontotemporal lobar
degeneration and an autopsy would help to determine this. The discovery of the
missense mutation in TDP 43 could provide targets for therapeutic methods in
Selective methods: PCR, DNA
Orly Lararov, Gerardo A.
Morfini., et al. (2007). impairments
in Fast Axonal Transport and Motor Neuron Deficits in transgenic Mice
Expressing Familial Alzheimer’s Disease-Linked Mutant Presenilin 1. The journal of Neuroscience, 27(26),
Presenilins (PS1 and PS2)
are multipass membrane proteins that regulate “y-secretase”, but have also
shown to play a role with intracellular trafficking of selected proteins. Mutations
of PS1 and PS2 have been shown to cause familial Alzheimer’s disease (FAD). Going on previous data of the motor in the
lumbar spinal cord of FAD-linked mutants, PS1 mice showed increase
phosphorylation of tau, neurofilaments, and two major cytoskeletal proteins. FAD-linked
mutant mice showed a very large impairment of axonal transport and resulted in
impaired motor performance. The ligation experiments revealed that PS1
mutations increased GSK-3 and kinesin-1 transport of proteins. FAD-mutant
showed impairment of anterograde fast axonal transport (FAT) of several
membrane proteins. Mainly Trk receptor and role in synaptic transmitions,
synaptic plasticity. Understanding of the FAD-mutants and PS1 impairments of
FAT may lead to better understanding of early onset Alzheimer’s Diseases.
Selected methods: Antibodes,
western blot, protein extraction, Rotorod test, Immunohistochemically analysis,
Stem Cell and development
Di Giorgio F. P., Carrasco
M. A., et al. (2007). Non-cell
autonomous effect of glia on motor neuron in an embryonic stem cell-based ALS
model. Nat Neurosci, 10(5), 608-614.
sclerosis (ALS) is a motor neuron disease (MND) and progressive
neurodegenerative disease that causes a loss of function in upper and lower
motor neurons which results in death. Most cases of the disease are not
genetically linked, with the exception of a few. From that few that are
genetically linked, most are caused by a dominant mutation in the gene for
super oxide dismutase (SOD1). Using embryonic stem cells (ESCs) from non-mutated
and mutated SOD1 gene in mouse development were studied to see the effects of
the mutation. Immunostaining and green fluorescent proteins showed the
development of the neuron cells. Glial and motor neuron cells were both watched
and grown in close proximity of each other. Those with the SOD1 mutation seemed
to be dying around fourteen days. The effect the SOD1 mutation had changed
glial cells to have an independent negative effect on motor neuron cell
Immunostaining, green fluorescent protein.
Mishra M., Paunesku T., et al. (2007). Gene expression analysis
of frontotemporal lobar degeneration of motor neuron disease type with ubiquitinated
inclusions. Acta Neuropathol, 114, 81-94.
(FTD) are diseases classified on protein deposits/inclusions. Protein miss
folding is one of the main causes of dementia related diseases. This study
compares effected frontotemporal lobar degeneration with uninitiated inclusions
(FTLD-U), frontotemporal lobar degeneration motor neuron disease(FTLD-MND), and
control subjects, using microarray, qRT-PCR, northern blot. qRT-PCR of three
genes that contribute to cytoskeleton proteins/filaments were observed, namely
DNAI1. The results of the qRT-PCR showed that DNAI1 was expressed three times
more in FTLD-U than FTLD-MND and controls. Apoptotic factors such as MDM4 and
protein p53 were altered in the FTLD-U and FTL-MND. DNALI1 was shown to
interact with TDP43 which has been shown to cause ubiquitinated inclusions.
Further research into the actions of DNALI1 and its interactions are needed.
The genes studied here could be targeted for therapeutic measures.
Selective methods: Northen
blot, case studies, RNA extraction, microarray hybrdaiztion, microarray data
analysis, qRT-PCR, statiscal analysis, PCR and cluster analysis.
Zhuang B., Su Y. S., et al. (2008). Motor Neuron Subtypes
through Transmembrane Semaphorin6A and PlexinA Signaling. Neuron, 61(3), 359-372.
Dendrites are part of
neurons that extend to reach the axon of neighboring neuron cells for cell
signaling. Although dendrites have many diseases associated with them such as
epilepsy and autism not much is not known about how they grow to connect the
axon of adjacent neuron cells. This study attempts to measure dendrite
regulation of growth of cell signaling with FERM, RhoDEF, and pleckstrin
homology domain protein 1 (Farp 1). Scientists made short hairpin RNAs (shRNAs)
targeted at Farp 1 and found a deregulation of Farp 1 decreased activity of
Farp1 by 91%. The shRNAs that targeted
Farp 1 showed 39% reduction in length of motor neurons. Both of these results
show that Farp 1 is involved in the regulation of neuron length. To determine whether Farp 1 controls dendrite
length two different signaling pathways, they used Sema6A/Plex44 and retinoid pathway. A ColP
assay reveals that Farp 1 signaling pathway is directly controls dendrite
Selective methods: RT-PCR,
Plasmids, Reverse northern blots, ColP Assay, Ligand production and receptor
binding, In Ovo electroporation and tissue Preparation, In Situ Hybridaztion
and immunohistochemistry, Primary Neuronal Cultures and Motor Neuron Analysis
Stich O., Kleer B., et al. (2007). Absence of paraneoplastic
antineuronal antibodies in ssera of 145 patients with motor neuron disease. J Neurol Nuerosurg Psychiatry, 78(8), 883-885.
syndromes (PNS) from cancer are believed to be correlated with autoimmune
effected neuronal tissues. This studies aims to identify if there is an
accumulation of paraneoplastic antineuronal antibodies (ANAbs) in patients with
motor neuron disease (MND). 222 patients with MNDs were evaluated and 145 of
those patients were chosen based on El Escorial criteria. An ELISA was
performed on the chosen 145 patients to determine the frequency of ANAbs in
patients with MNDs. From patients that were previously diagnosed PNS, 21 had
high antineuronal antigen reactivity. None of the other MND patients showed a
high antineuronal antigen reactivity. From the six ELISAs preformed none of the
patients showed to have a high frequency antineuronal antigen. These results
demonstrate that it would not be necessary to screen patients with MNDs to for
ANAbs as the only ones to be detected were ones with previously occurring PNS.
Selective methods: ELISA,
Haramati S., Chapnik E., et al. (2010). miRNA malfunction causes
spinal motor neuron diseases. PNAS, 107(29),
One of the most heavily
regulated posttranscriptional processes is micro-RNA (miRNA), due to their
abundance and their regulation of downstream targets. This study looks at
defective RNA metabolism and its ability to have ALS pathogenic traits.
Deregulation of miRNAs could affect RNA metabolism. They performed a lose it
experiment by deleting the Dicer1 gene, which is known to regulate miRNA. Using
an electromyography (EMG) the mice with deleted Dicer1 gene showed frequent
fibrillation. Fibrillation has been identified in animals with progressive
locomotive deterioration. Looking at the motor neurons (MNs) of the spinal cord
of deleted Dicer1 mice showed a significant decrease in number of MNs. This
study shows the importance of miRNAs and their function of regulation in motor
neuron development and RNA metabolism. This could be target for treatment of
motor neurological diseases.
Selective methods: Lose it
experiment, Microarray, Electromyography, spinal cord histology.
Hanada, T., Weitzer S., et al. (2013) The RNA kinase
CLP1 links tRNA metabolism to progressive motor neuron loss. Nature, 495(7442): 474-480.
One of the known functions
of Clp1 is to be a RNA kinase in mammals and archaebacterial; the other function
of Clp1 was not known. To find out the function they generated transgenic mice
to have a mutant Clp1 and called it Clp1 (K/K). All Clp1 (K/K) expressed
nonfunctional neuro muscular junctions in the diaphragm that then caused
respiratory failure and lead to neonatal death. They successfully got
homozygous Clp1 (K/K) that were able to survive after birth, but exhibited a
loss in motor functions. The viable Clp1 (K/K) spinal cords were to tested and
found a buildup tyrosine tRNA fragments. tRNA fragments were also linked to
oxidative stress and activating p53 tumor suppressor pathway. By deactivating
the p53 pathway and reducing the oxidative stresses they were able to recover
the function of the motor neurons. The tRNA processing helps neural metabolism.
generation of transgenic mice, phenotyping, pre-tRNA splicing, Northern blot,
identification of tyrosine tRNA fragments.
Membrane structure and function
Laird F.M., Farah M. H., et al. (2008). Motor Neuron Disease Occurring in Mutant Dynactin
Mouse Model Is Characterized by Defects in Vesicular Trafficking. The Journal of Neuroscience, 28(9),
Familial amyotrophic lateral
sclerosis (ALS) has been linked to a mutation in p150 glued of the dynactin complex. Dynactin p150 glued is part of a multiprotein complex that separates with
dynein and is required for retrograde transport of vesicles on the membrane. This
study generated transgenic mice with a mutation in the p150 glued gene and traced the cells with immunostaining
procedures. Immunostaining revealed a very large accumulation of membrane
vesicle structures at five months of age. This research is important because it
shows that a p150 mutation results in a buildup of vesicles that causes axonal
swelling. The results also show that cell counts diminished and there is a possibility that the neuron
cell been autophagic characteristics. This study proves that the pl150 glued mutation can contribute to neuron cell death.
Generation of transgenic mice, SDS-PAGE, Immunoblotting, immunocytochemistry, electrography,
muscle histology, neuron histology, immunofluorescence.